Centrifugal pumps are well known apparatus for the pumping of fluids such as gases, liquids and suspensions by the rotation of an impeller within a volute. The fluid to be pumped passes along a flow path extending from central inlet to the impeller, whence the fluid is expelled at a high rate centrifugally outward against a surrounding volute which opens to a horn leading to the pump outlet. Although all parts of the pump housing and components are subjected to wear, particularly when pumping finely particulate materials such as slurries or suspensions of coal, some parts by virtue of their location are particularly subject to erosive wear, i.e. wear caused not so much by large particle abrasion as by millions of minute contacts by the small particles which characterize fine particulate slurries. One area receiving considerable erosive contact is the cutwater, the sharply angled divider between the volute and the outlet horn; another area highly subject to erosion is on the wear rings on which the impeller turns; another is the impeller itself, the volute wall surrounding it, and those other areas where particle impact is at relatively higher velocities or frequency.
Typically, the pump housing and pump components are fabricated of steel, generally a carbon steel, and sometimes an iron base stainless steel. Such pumps can be improved in erosion wear resistance in accordance with the invention.
Importantly, the erosion resistance benefits conferred by the invention can be obtained locally in areas needing them, so that the entire pump need not be fabricated of exotic materials, nor coated entirely with a specialized coating which in fact is needed only here and there.